Unit 6: Molecular Genetics

Question 1

What does DNA stand for

Answer 1

Deoxyribose nucleic acid

Question 2

What does RNA stand for

Answer 2

Ribose nucleic acid

Question 3

What are the 3 components of a DNA monomer

Answer 3

Nitrogenous Base (A,T,G,C), Sugar, Phosphate

Question 4

What type of bond links nitrogenous base

Answer 4

Hydrogen Bonds

Question 5

How many hydrogen bonds link A and T/U

Answer 5

2

Question 6

How many hydrogen bonds link together G and C

Answer 6

3

Question 7

On what molecule of DNA is 5’ end always on

Answer 7

Phosphate

DNA strands run Antiparallel

Question 8

On what molecule of DNA is 3’ end always on

Answer 8

The OH of Phosphate

DNA strands run Antiparallel

Question 9

Overall purpose of DNA

Answer 9

Contains coded information that programs all cell activity

Question 10

Overall purpose of RNA

Answer 10

Functions in the actual synthesis of proteins coded by DNA

Question 11

State 3 differences between prokaryotes and eukaryotes

Answer 11

Circular DNA : Linear DNA
Replication occurs in cytoplasm : Replication occurs in nucleus
No histones : DNA wrapped around histones
Supercoiled DNA : Forms Chromatin

Question 12

What is the political beliefs of DNA

Answer 12

Semi-conservative - Daughter DNA molecules each consist of one parental strand and one new strand

Determined by Meselson and Stahl

Question 13

What end is the Leading strand

Answer 13

5’

Question 14

What is the function of the helicase

Answer 14

To unzip the parental strand

Question 15

When is DNA replicated

Answer 15

for mitosis or meiosis

Question 16

The ___ strand is synthesized continuously by __________

Answer 16

Leading Strand/5’; DNA Polymerase

Question 17

On the Lagging strand, Primase places a RNA primer in which DNA polymerase begins to synthesize an _____ from the ___’ end to the ___’ end

Answer 17

okazaki fragment: 3’; 5’

Question 18

What is the function of DNA Ligase

Answer 18

To join the Okazaki fragment with the growing strand

Question 19

What is the function of the Topoisomerase

Answer 19

To relax the supercoiled DNA and unwind it so the Helicase can unzip it.

Question 20

What are the main steps of gene expression

Answer 20

DNA–> RNA using Transcription
Introns are cut out by Spliceosomes, creates mRNA
End caps are put on and mRNA is exported out of the nucleus
mRNA is the Translated to create an amino acid chain

DNA–>RNA–>mRNA–>Protein

Question 21

What is a mRNA triplet also called?

Answer 21

Codon

Question 22

What direction does RNA polymerase read in and on what strand?

Answer 22

From 3’ to 5’ on the non-coding strand

Question 23

What reads mRNA in the cytoplasm?

Answer 23

A ribosome

Question 24

What are the binding sites on the ribosome during translation

Answer 24

E,P,A

Question 25

What molecule brings matching codons and amino acid to the binding site?

Answer 25

tRNA

Question 26

The binding site ___ forms a ___ that will later make a protein

Answer 26

P; amino acid chain

Question 27

The binding site ___ forms a ___ with the binding site __ to add to the __ chain

Answer 27

P; peptide bond; A; amino acid/polypeptide

Question 28

What happens to the protein after translation?

Assume it is leaving the cell

Answer 28

It goes to the Golgi complex where it is prepared for use out of the cell, is transported via vesicle to the cell membreane and then undergos exocytosis

Question 29

Describe a point mutation

Answer 29

One nucleotide error, substitutions

Ex. A instead of G

Question 30

Describe a Frameshift Mutation

Answer 30

One or more base is deleted or inserted

May alter reading frame –> disastrous effect on resulting protein

Question 31

Missense Mutation vs Nonsense Mutation

Answer 31

Missense still codes for an amino, just not the correct one; Nonsense changes amino acid codon into a stop codon - leads to a nonfunctional protein

Question 32

What are some Large-Scale Mutations and where did their errors occur?

Answer 32

Deletion - loss of a chromosomal segment - Replication
Duplication - repetition of a segment - Replication
Inversion - reverses a segment - Crossing Over
Translocation - Moves segment from one chromosome to a non-homologous chromosome - Crossing over

Question 33

What are the 4 steps of translation and their function?

Answer 33

Initiation - Start codon binds to ribosome, tRNA carrying Met attatches to P site, lage subunit attatches
Elongation - consists of codon recognition and peptide bond formation
Translocation - tRNAs shift over a site
Termination - Polypeptide release

Question 34

What are the 2 types of operons in prokaryotic regulation and what do they mean?

Answer 34

Inducible: a lac operon binds to the repressor presend and allows the gene to be expressed (off until bound)
Repressible: Corepresessor binds to the repressor to prohibit gene expression (on until bound)

Question 35

How do eukaryotes use gene regulation?

Answer 35

Transcription factors bind too DNA sequences and other regulatory regions (both + and -)

Question 36

How do viruses enter the cell and what do they do?

Answer 36

Bacteriophages inject viral DNA into host cell, replicates and manufactures capsid proteins in order to assemble new virus and exit cell